Powder delivery apparatus and method



Nov. 7, 1961 F. T. WARD El'AL 3,007,744

POWDER DELIVERY APPARATUS AND METHOD Filed Oct. 22, 1959 2 Sheets-Sheet 1 FIG. I

INVENTORS. FRANK T. WARD ROBERT C. READ BWKM/Q THEIR ATTOR NEY.

Nov. 7, 1961 F. T. WARD ETAL 3,007,744

POWDER DELIVERY APPARATUS AND METHOD Filed Oct. 22, 1959 2 Sheets-Sheet 2 INVENTORS.

FRANK T. WARD ROBERT C. READ THEIR ATTORN EY.

United rates Patent Ofifice 3,007,744 Patented Nov. 7, 1961 3,007,744 POWDER DELIVERY APPARATUS AND METHOD Frank '1. Ward, Wilton, and Robert C. Read, Norwalk,

Conn, assignors to The Gordon Company, Inc., Norwalk, Conn, a corporation of Connecticut Filed Oct. 22, 1959, Ser. No. 848,146 15 Claims. (Cl. 30253) This invention relates to an apparatus and method for incorporating finely divided dusting powders into an airstream with a substantial measure of uniformity. The apparatus and method of the present invention has a variety of uses and it will be described in connection with an apparatus and system for applying starch powder to pieces of dough and the conveyors therefor in the commercial baking of bread. The invention, broadly considered, is an improved means of transporting finely divided dry powders by means of an airstream. It can be used to convey dry powder from place to place at ac curately controlled rates regardless of the purpose for which they are transported.

An important object of the present invention is to provide an improved system of applying powdered materials to surfaces wherein the amount of powder in the airstream can be increased and decreased at the will of the operator and at any rate of flow and wherein the concentration of powder in the stream will be substantially uniform and wherein the stream may be stopped and later restarted without any appreciable change in the rate of flow after re-starting.

Another object of the present invention is to provide an apparatus for delivering powder by means of an airstream and which is adjustable so as to permit delivery of powder almost at atmospheric pressure and zero velocity at the point where it is applied. This insures a minimum escape of powder into the room or other area where the powder is applied.

Another object of the invention is to provide a system of the character described wherein the surfaces which are contacted by the powder have no moving parts, no complex valves, and no small orifices or ducts which, as is well known in the art, have a tendency to clog and stop operation of the powder applying apparatus completely.

Yet another object of the invention is to provide a powder-dusting apparatus wherein the powdered material is so uniformly dispersed in the airstream as to permit delivery of the powder to articles close at hand or at points removed from the apparatus.

In the drawing:

FIG. 1 is a side elevation, partly in section, showing a starch tank embodying the present invention and the other component parts of the system.

FIG. 2 is a broken section showing the lower end of the tank.

FIG. 3 is a bottom view of a tank having plural powderdelivering assemblies on its lower wall.

The tank is shown at and it is provided at its upper end with a tightly fitting cover 11 which is removed when the tank is to be charged with powder. The cover is held in closed position by a plurality of clamps 13. The lower wall 15 of the tank may be curved as shown and has an opening 17 of substantial size (i.e., a diameter of the order of 2 inches).

A closed tubular chamber 18 of inverted T-shape and having an intermediate vertical conduit'l9 is positioned below this lower wall with the upper end of the conduit secured at the edges of opening 17 as by welding. This opening should be located substantially in the center of lower wall 15 unless more than one of the tubular chambers 18 are employed in the system, in which case they may be spaced one at the center and the others at equal distances on either side of the center along a common diameter, and with the leg of the inverted T kept vertical. This chamber may be formed from an ordinary 2" unthreaded soldered T pipe fitting and is provided at its inlet end with a soldered nipple 20 and an air-tight fitting cap 21 is secured to the nipple by a set. screw 23. The cap has a threaded opening 25 to receive an externally threaded tube 27 forming a nozzle and a locknut 28 secures the tube in an adjusted, fixed position within the chamber. The locknut, when tightened, also makes air tight the passage of tube 27 through cap 21.

At the other end of the chamber another soldered nipple 29 is positioned to which is soldered an angular fitting 30 having a fixed reducing bushing 31 at its outer end. The bushing receives one end of a delivery tube 33 for the starch powder, to which it is soldered. The nozzle 27 which is of considerably smaller diameter than chamber 18 has a T fitting 3-5 at its inner end and a plate 37 having a small orifice 38 is soldered to the upper end of the intermediate or branch section of the T. This section is also fitted with a self-closing valve member 39 made preferably from rubber or other resilient material and having a slot 40 forming an orifice that closes whenever air pressure is reduced in tube 27, thereby preventing either air or powder, or air and powder, from entering tube 27. This valve is similar to rubber closures commonly used on compressible mucilage containers and which opens when the pressure of the fluid is applied by squeezing the container and then closes when the pressure is released. The valve permits air to flow from the inlet end through the outer orifice but denies any return flow. The fitting 35 further supports a tube 41 aligned with tube 27 and mounted in spaced relation to the closed tubular housing 18 and having a similar apertured plate 43 and rubber valve 45 at its outer end.

If the chamber 18 has an inside diameter of 2" the externally threaded tubes 2741 may have /8" pipe diameter and the openings in plates 37-43 a diameter of about The distance from the axis of tube 27 to the upper face of valve 39 may be about 78" and delivery pipe tube 33 is preferably of a minimum inside diameter of All these dimensions are closely approximate.

Air under suitable pressure is supplied to the dusting system through a pipe 47 leading from a supply line. In bakery installations the all-purpose air supply line is generally maintained at p.s.i., or even higher, and since this is a higher pressure than is required for the dusting system it may pass through a pressure reducing valve (not shown) to reduce the pressure to about 25 psi. After leaving the reducing valve the air may pass through an air filter and a solenoid valve for discontinuing operation of the dusting system when desired.

The air under pressure thus enters the system through pipe 47 and between this pipe and delivery pipe 48 there is positioned a valve 50 for manually controlling pressure and a pressure gauge 51. Delivery pipe 48 is connected with a fitting 53, which in turn is connected with nozzle 27 and with a branch line 55 so as to direct air from the supply line into the tank in two areas, one of which is below the column of starch through central opening 17 in the lower wall of the tank, and the other is above the column of starch and enters the tank through a pipe 57 connected with branch pipe 55 and which has a downwardly extending terminal 58. The level of the powder shown at L is always below the orifice of this terminal. Valve 50 is the valve by which the operator controls the rate of fiow of the powder to the place of powder application.

Branch pipe 55 supplies air from hand adjustable pressure regulating valve 50 to adjustable pressure regulating valve 63. Valve 63 in turn supplies air under pressure to lines 57 and 60, to opening 58, to gauge 61, and to pressure relief valve 62. Valves 63 and 62 are of great importance because they maintain the air pressure at the top of tank above the powder, at a value that will permit constant air flow upward through the starch powder via opening 17 from nozzles 38 and 43, thereby keeping aerated the powder in tank 10 while at the same time insuring adequate air pressure on top of the aerated powder to keep it flowing out through opening 17, chamber 18, elbow 30, and bushing 31, and starch line 33, to the destination of the powder. When the settings of pressure regulating valve 63 and pressure relief valve 62 have been determined by trial at the bakery to provide the range of pressures for which pressure regulating valve 50 may have to be adjusted bythe operator to give adequate maximum and minimum rates of powder delivery at the dusting point or points, then pressure regulating valve 63 and pressure relief valve 62 are locked by means of their locknuts at their so-determined settings. Pressure value of these combined settings of valves 63 and 62 and the influence of air pressure from tank opening 17 (valve 50) can be read on gauge 61. For example, the operator may find that with pressure regulating valve 50 set at 3 p.s.i., and with valves 63 and 62 set to show a pressure of 1 p.s.i., he obtains the correct minimum rate of powder delivery. If thereafter the stickiness of the dough pieces being processed becomes greater, the operator may find it necessary to increase the pressure setting of valve 50 to, say, 4 p.s.i. on gauge 51. Examination of gauge 61 may then show that the pressure in the top of tank 10 has risen to 1 A p.s.i. The pressure setting of valve 63 is always maintained at a lower value than the pressure setting of valve 50, so that the air supplied to the top of tank 10 always is supplied at a pressure lower than the pressure of air supplied to the nozzle orifice 38, under the tank 10. Further, because of the interconnection of supply to valve 63 and line 55 leading from valve 50, air can only be supplied to the top of tank 10 when air at the higher pressure is being supplied to nozzle orifices 38 and 43 under tank 10, thus eliminating any condition under which the pressure of the air above the powder could exceed the pressure of the air supplied to the area under the powder, which would tend to pack the powdered material within the tank and hamper or halt the flow of powder into the chamber under tank 10. Flow relief valve 62 is adjusted in conjunction with valve 63 so that, excepting when tank 10 is empty allowing top-of-tank air to escape freely through duct 19, chamber 18 and empty starch delivery lines 33, relief valve 62 will remain slightly open and normally vent a minute amount of air so long as air is being supplied through line 55 and valve 63 to the space in the top of tank 10 above the powder. Obviously, when the apparatus is set up, such trial adjustments as above must be made, and when they have been properly determined the locknuts on valves 63 and 62 are set and thereafter the bakery employee has to manipulate only valve 50 in order to take care of any degree of dough stickiness. In other words, because of the difference between commercial varieties of dusting starch powder, and because of the difference between starch powders as received from the manufacturers and starch powder as reclaimed from dust collectors, it is necessary to make the preliminary cut and try adjustment of valves 63 and 62, so that the operator will thereafter be able to ob-taina range of starch delivery rate to meet any bakery conditions that may exist.

Observation of gauge 61 during normal operation will show rather rapid vibration of the gauge needle over a small range (a few ounces), indicating the minor variations in pressure continually occurring in tank 10 due to movement of the powder from tank 10 into powder delivery line 33 and the combined effects of the pressure settings at valves 50, 63 and 62, and of the orifice sizes in plates 37 and 43, and the static head and friction head in powder delivery line 33.

The combination of this top tank pressure and the aerating effect of air escaping upwardly from vertical orifice 38 provides a steady and reliable downward flow of aerated starch powder out of tank 10 into starch chamber 18 and, aided by additional air from the horizontal orifice in plate 43 and orifice 38 causes a flow of the starch-air mixture outwardly and upwardly through starch delivery pipe 33 to the cluster hoods to provide the amount of dusting starch required to keep dough from sticking to the bakery equipment.

Movement of air delivery tubes 2741 inwardly or outwardly of chamber 18 to an adjusted, fixed position has been mentioned. This movement necessarily modifies the positioning of horizontal nozzle 43 relative to the forward end of the chamber and of nozzle 38 relative to the area of duct 19 leading upwardly through opening 17 into the tank. As this whole nozzle assembly is moved rearwardly from the position shown in FIG. 2 toward the center line, it increases the amount of starch delivered without the necessity of increasing the air volume or air pressure. On the other hand, if nozzle 38 were moved forwardly from the position of FIG. 2 until it is outside the area of vertical duct 19 (i.e., under the roof afforded by the upper wall of chamber 18), the flow will stop. Regardless of whether nozzle 38 is moved toward the rear edge of the area of duct 19, for maximum delivery, or aligned under the forward edge of duct 19, and almost under the roof, for minimum but non-failing delivery, any accumulation of powder in the chamber to the rear of duct 19 has no influence on the continuing operation of the device.

It was earlier pointed out that instead of the single chamber 18 at the middle of the lower wall of the tank, a plurality of such chambers may be provided. This arrangement is shown in FIG. 3 wherein chamber 18a is positioned substantially at the center of the lower wall and chambers 18b and are positioned equally distant from the center. Each one communicates with an opening (not shown) in the tanks lower wall, similar to opening 17. This is believed to be the first system wherein a single tank can be used to feed two or more separate powder lines.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that many modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.

What we claim is:

1. An apparatus for delivering air with powdered material incorporated therein comprising a delivery pipe, a closed tank for the powdered material and having an opening in its lower wall, an elongated closed chamber below the tank and having a central branch conduit leading upwardly to said opening, a nozzle comprising an air tube of lesser diameter than the chamber leading into said chamber from one end thereof and provided with a branch tube having an orifice leading upwardly within the area of said branch conduit, said nozzle having an orifice at its outer end which is located near the opposite end of the chamber, said delivery pipe being connected with said opposite end, an air supply conduit connected with the opposite end of said tube, and a branch pipe leading from the air supply conduit to the upper end of said closed tank, and a pressure regulating valve and a pressure relief valve in said branch pipe.

2. The apparatus defined in claim 1 and wherein the tube leading into the chamber is longitudinally adjustable.

3. The apparatus defined in claim 1 and wherein the position of the upwardly leading orifice of the branch tube is adjustable toward and away from the center line of the branch conduit.

4. The apparatus defined in claim 1 and wherein the position of the orifice at the outer end of the tube is adjustable toward and away from the delivery pipe.

5. The apparatus defined in claim 1 and wherein each orifice is of smaller dimensions than the diameter of the air tube.

6. The apparatus defined in claim 1 and wherein each orifice is fitted on its lower pressure side with a normally closed, non-return valve.

7. The apparatus defined in claim 1 and wherein the air tube is externally threaded and is supported by a threaded sleeve whereby rotation of the tube moves the orifices inwardly or outwardly of the chamber.

8. The apparatus defined in claim 1 and wherein each orifice is fitted with a plate having an opening of smaller diameter than the air tube and with a self closing valve which permits flow of air out of the air tube and into the chamber but prevents reverse flow of the air and powder.

9. An apparatus for transporting finely divided powders by means of an airstream and comprising a delivery pipe, a closed tank for the powdered material, a closed chamber below the tank and having a branch conduit leading upwardly to said tank, a nozzle leading into said chamber from one end thereof and provided with an orifice leading upwardly toward the tank within the area of said branch conduit and a second orifice at its outer end which is located near the opposite end of the chamber, said delivery pipe being connected with said opposite end, an air supply conduit connected with said nozzle, a branch pipe leading from the air supply conduit to the upper end of said closed tank, and a pressure regulating valve and a pressure relief valve in said branch pipe.

10. The apparatus defined in claim 9 and provided with a pressure relief valve in said branch pipe.

11. The apparatus defined in claim 9 and wherein the nozzle leading into the chamber is longitudinally adjustable.

12. The apparatus defined in claim 9 and provided with a pressure relief valve and a pressure regulating valve in said branch pipe.

13. The apparatus defined in claim 9 and wherein a plurality of said closed chambers with nozzles are provided at the lower end of the tank.

14. The apparatus defined in claim 9 and wherein the position of the orifice at the outer end of the nozzle is adjustable toward and away from the delivery pipe.

15. The apparatus defined in claim 9 and wherein each orifice is fitted on its lower pressure side with a normally closed, non-return valve.

References Cited in the file of this patent UNITED STATES PATENTS 749,206 Limbert Jan. 12, 1904 1,933,543 Anderson Nov. 7, 1933 1,942,379 Thompson Jan. 2, 1934 2,500,271 Bozich Mar. 14, 1950 2,584,378 Beam Feb. 5, 1952 2,786,721 Davis Mar. 26, 1957 2,850,329 Pyle Sept. 2, 1958 

